Try to find questions that have little content for answering online. Make sure to follow the basic SEO rules (there are tons of apps out there that can assist with this).
You should also have many social media accounts, try to be as active as possible and post your blog link whenever you have new content.
I believe that is the best way to get started and start to reach out to different avenues that many have listed here.

This is half the battle, but incredibly almost no one ever mentions it. A seasoned writer that knows the subject inside out, one that is worth the money he/she charges, is difficult to find, but can make all the difference.

To increase your blog traffic ethically you have to do the following offpage strategies
1- Share with your friends & family.
2- Create Useful blogs or articles which will help your audience.
3- blog Directories - Their are many blog directories available you can submit your blog link on such sites.
there are many more strategies to build your traffic.

One idea I really like is guest blogging. Really beneficial for both parties, you offer to write a blog on someone else's blog (and make it good and informative and useful) and they write one on yours. You get a lot of crossover and it really works.